TrieEntry higherEntry()

in src/main/java/org/apache/commons/collections4/trie/AbstractPatriciaTrie.java [1636:1685]
39 lines of code
10 McCabe index (conditional complexity)

    TrieEntry<K, V> higherEntry(final K key) {
        // TODO: Cleanup so that we don't actually have to add/remove from the
        //       tree.  (We do it here because there are other well-defined
        //       functions to perform the search.)
        final int lengthInBits = lengthInBits(key);

        if (lengthInBits == 0) {
            if (!root.isEmpty()) {
                // If data in root, and more after -- return it.
                if (size() > 1) {
                    return nextEntry(root);
                }
                // If no more after, no higher entry.
                return null;
            }
            // Root is empty & we want something after empty, return first.
            return firstEntry();
        }

        final TrieEntry<K, V> found = getNearestEntryForKey(key, lengthInBits);
        if (compareKeys(key, found.key)) {
            return nextEntry(found);
        }

        final int bitIndex = bitIndex(key, found.key);
        if (KeyAnalyzer.isValidBitIndex(bitIndex)) {
            final TrieEntry<K, V> added = new TrieEntry<>(key, null, bitIndex);
            addEntry(added, lengthInBits);
            incrementSize(); // must increment because remove will decrement
            final TrieEntry<K, V> ceil = nextEntry(added);
            removeEntry(added);
            modCount -= 2; // we didn't really modify it.
            return ceil;
        }
        if (KeyAnalyzer.isNullBitKey(bitIndex)) {
            if (!root.isEmpty()) {
                return firstEntry();
            }
            if (size() > 1) {
                return nextEntry(firstEntry());
            }
            return null;
        }
        if (KeyAnalyzer.isEqualBitKey(bitIndex)) {
            return nextEntry(found);
        }

        // we should have exited above.
        throw new IllegalStateException("invalid lookup: " + key);
    }